A woman uses a face masks as a preventive measure against the spread of the new coronavirus, COVID-19, in Bogota, on March 19, 2020. Colombia will block all international flights from Monday for 30 days, President Ivan Duque announced on Thursday. (Photo by Raul Arboleda/AFP Photo)

Protesters begin to gather ahead of the UK Student Climate Network's Global Climate Strike at Millbank in London, England on September 20, 2019. (Photo by Gareth Fuller/PA Images via Getty Images)

A group of colourful dancers from the Kumari Shiksha Dance Institution light colourful clay lamps in preparation to celebrate Diwali during the two day Diwali (Festival of Lights) Hindu festival celebrations at the old Drive-Inn in Durban, on October 19, 2019. The two-day festival attracts over 100,000 visitors. The festival celebrations include, parading of floats, chariots, singing of devotional songs, dances, games, face painting, food stalls of vegetarian food, clothing, display of toys and jewellery. Young people also get the opportunity to showcase their cultural and spiritual talents. A billion Hindus worlwide will officially celebrate Diwali on 27 October 2019. (Photo by Rajesh Jantilal/AFP Photo)

A pilot looks up from a U.S. F-22 Raptor fighter as it prepares to refuel in mid-air with a KC-135 refuelling plane over European airspace during a flight to Britain from Mihail Kogalniceanu air base in Romania April 25, 2016. (Photo by Toby Melville/Reuters)

U.S. Air Force Major Paul “Loco” Lopez performs in an F-22 Raptor during the AirPower Over Hampton Roads JBLE Air and Space Expo at Joint Base Langley-Eustis, Virginia, U.S. May 18, 2018. (Photo by U.S. Air Force/Staff Sgt. Areca T. Bell/Handout via Reuters)

A female Chinese People's Liberation Army soldier looks at members of an honor guard preparing for a welcome ceremony for visiting German President Joachim Gauck, outside the Great Hall of the People in Beijing, Monday, March 21, 2016. (Photo by Andy Wong/AP Photo)

Protesting university students flee as police fire stun grenades outside Parliament in Cape Town, South Africa, Wednesday October 21, 2015. The protests are part of a wave of nationwide protests that have shut down many South Africa universities, which say they are struggling with higher operational costs as well as inadequate state subsidies. (Photo by AP Photo)

Costumed revelers pose in front of the Chapell bridge on the opening day of the carnival in Lucerne, Switzerland, 20 February 20​20. The carnival takes place in Lucerne from 20 to 25 February 2020. (Photo by Alexandra Wey/EPA/EFE)